The present invention relates to temperature sensing of food items that are heated or warmed using induction-based food warming and holding units. More particularly, the invention relates to non-contact temperature measurement of such food items using infrared (IR) temperature sensing.
Direct contact temperature sensing of induction-heated food items is known using, for example, resistive thermal devices (RTDs). However, traditional temperature sensing technologies used with food and holding techniques are hindered by inaccuracy. These methods have slow response times, require expensive accessories and/or are subject to unrealistic requirements such as maintaining a perfectly flat bottom pan. Additionally, direct contact temperature sensing methods make accurate temperature readings difficult or impossible when dealing with induction-heated cookware having underside surface height variations, as with porcelain cookware.
Accordingly, while IR temperature sensing for induction-based food warming and holding units would have several advantages, including solving the deficiencies of direct contact temperature sensing methods, it also introduces several technical challenges that must be overcome in order to have a functional, real-world solution in the induction-based food warming/holding environment. For example, the IR sensor should be located in a position so that it can sense the warmest part of the object whose temperature is to be measured, and its radiated emissivity levels must be capable of being monitored in a way that accounts for environmental distortions, such as the presence of covers/shields, and the use of differing materials comprising the food warming/holding units. Other technical hurdles, also mentioned below, had to be overcome as well.
Accordingly, it would be advantageous to provide an IR temperature sensing apparatus and method that would allow non-direct contact temperature sensing of induction-heated food objects located in food warming/holding units.